1. Field of the Invention
The present invention relates to an image forming apparatus, an image processing apparatus, and a control method therefor, as well as a computer-readable storage medium storing a program for implementing the control method.
2. Description of the Related Art
As a cleaning method for use in an electrophotographic image forming apparatus, there is known a cleaning method in which toner is forcefully jetted from a developing device on a regular basis, and the toner is supplied to a cleaning blade of a photosensitive drum.
When a number of images with low print rate are printed, toner supplied to a developing roller from a toner container is left without being transferred, and deteriorated toner is accumulated on the developing roller.
When printing remains unperformed with the accumulated toner in the developing roller left standing, fusion of toner to the developing roller occurs due to an increase in the power with which the accumulated toner is attached to the developing roller, and an image defect which is so-called a fusion stripe may be formed in the area of toner fusion. Accordingly, in an image forming apparatus, it is necessary to perform cleaning in which toner is forcefully jetted to remove toner left on the developing roller on a regular basis.
Moreover, for example, when printing with low print rate continues, or when printing in a hot and humid environment continues, phenomena such as curling of a cleaning blade of a photosensitive drum or an intermediate transfer belt, chipping of an edge portion of the cleaning blade, and cleaning failure occur.
It is known that to cope with such phenomena, toner jetted from a developing device is distributed among a cleaning blade, an intermediate transfer belt, and so on using the cleaning method described above, and the distributed toner is used as a lubricant to prevent curling, cleaning failure, and so on described above.
As a method to control jetting of toner in the cleaning method described above, there is known a method in which toner is jetted so as to form a predetermined pattern held by an image forming unit that forms images so that a predetermined amount of toner can be forcefully consumed (see, for example, Japanese Laid-Open Patent Publication (Kokai) No. H09-034243).
According to the method disclosed in Japanese Laid-Open Patent Publication (Kokai) No. H09-034243, however, because toner is jetted according to a predetermined pattern held by the image forming unit, it is difficult to jet a small amount of toner, jet a large amount of toner, and partially increase or decrease the amount of toner jetted.
Moreover, when a toner jet pattern is selected according to an image to be printed, an optimum toner jet pattern can be selected based on the information on the image to be printed. In this case, however, because no consideration is given to a usage environment of an image forming apparatus, there is a problem that no optimum toner jet pattern suitable for a usage environment of the image forming apparatus having an image forming unit is created.
Further, because an image forming unit normally has a poor resource for holding data, it is difficult for the image forming unit to hold, in advance, an optimum toner jet pattern suitable for a usage environment of an image forming apparatus, or the like.